If you have the programming guides available, or can get your hands on them, you can try resetting / reapplying the programming. That has helped us with both Motorola and Datalogic scanners in the past.
How many samples have you tested? Since most scanners are just keyboard emulators, it seems unlikely to me to be an issue with Leap specifically. Unless your web browser has some auto-fill extensions turned on, maybe those could possibly be interfering with data input.